{"id":36271,"date":"2019-10-31T22:10:36","date_gmt":"2019-10-31T19:10:36","guid":{"rendered":"https:\/\/prohoster.info\/blog\/uyazvimost-v-proshivkah-bmc-kontrollerov-zatragivayushhaya-servery-mnogih-proizvoditelej\/"},"modified":"2019-10-31T22:10:36","modified_gmt":"2019-10-31T19:10:36","slug":"uyazvimost-v-proshivkah-bmc-kontrollerov-zatragivayushhaya-servery-mnogih-proizvoditelej","status":"publish","type":"post","link":"https:\/\/prohoster.info\/cs\/blog\/news\/uyazvimost-v-proshivkah-bmc-kontrollerov-zatragivayushhaya-servery-mnogih-proizvoditelej","title":{"rendered":"Zranitelnost ve firmwaru BMC kontrol\u00e9r\u016f, kter\u00e1 se t\u00fdk\u00e1 server\u016f mnoha v\u00fdrobc\u016f","gt_translate_keys":[{"key":"rendered","format":"text"}]},"content":{"rendered":"

Spole\u010dnost Eclypsium odhalila<\/a><\/noindex> Dv\u011b zranitelnosti ve firmwarech BMC kontrol\u00e9ru dod\u00e1van\u00e9ho v serverech Lenovo ThinkServer, kter\u00e9 umo\u017e\u0148uj\u00ed m\u00edstn\u00edmu u\u017eivateli vym\u011bnit firmware nebo prov\u00e9st libovoln\u00fd k\u00f3d na stran\u011b \u010dipu BMC.<\/p>\n

Dal\u0161\u00ed anal\u00fdza uk\u00e1zala, \u017ee tyto probl\u00e9my se t\u00fdkaj\u00ed i firmwarech BMC kontrol\u00e9r\u016f pou\u017e\u00edvan\u00fdch v serverov\u00fdch platform\u00e1ch Gigabyte Enterprise Servers, kter\u00e9 jsou tak\u00e9 vyu\u017e\u00edv\u00e1ny ve serverech firem jako Acer, AMAX, Bigtera, Ciara, Penguin Computing a sysGen. V problematick\u00fdch BMC kontrol\u00e9rech byly pou\u017eity zraniteln\u00e9 firmwary MergePoint EMS, vyvinut\u00e9 extern\u00edm dodavatelem Avocent (v sou\u010dasnosti je sou\u010d\u00e1st\u00ed spole\u010dnosti Vertiv). <\/p>\n

Prvn\u00ed zranitelnost je zp\u016fsobena absenc\u00ed kryptografick\u00e9 verifikace stahovan\u00fdch aktualizac\u00ed firmwaru (pouze se pou\u017e\u00edv\u00e1 kontrola CRC32, na rozd\u00edl od doporu\u010den\u00ed<\/a><\/noindex> NIST, kter\u00fd pou\u017e\u00edv\u00e1 digit\u00e1ln\u00ed podpisy), co\u017e umo\u017e\u0148uje \u00fato\u010dn\u00edkovi s m\u00edstn\u00edm p\u0159\u00edstupem k syst\u00e9mu vym\u011bnit firmware BMC. Tento probl\u00e9m m\u016f\u017ee b\u00fdt nap\u0159\u00edklad vyu\u017eit k hlubok\u00e9 integraci rootkitu, kter\u00fd z\u016fst\u00e1v\u00e1 aktivn\u00ed po p\u0159einstalaci opera\u010dn\u00edho syst\u00e9mu a blokuje dal\u0161\u00ed aktualizace firmwaru (k odstran\u011bn\u00ed rootkitu je nutn\u00e9 pou\u017e\u00edt program\u00e1tor pro p\u0159eps\u00e1n\u00ed SPI flash).<\/p>\n

Druh\u00e1 zranitelnost je p\u0159\u00edtomna v k\u00f3du aktualizace firmwaru a umo\u017e\u0148uje podstr\u010den\u00ed vlastn\u00edch p\u0159\u00edkaz\u016f, kter\u00e9 budou provedeny v BMC s nejvy\u0161\u0161\u00edmi privilegii. Pro \u00fatok sta\u010d\u00ed zm\u011bnit hodnotu parametru RemoteFirmwareImageFilePath v konfigura\u010dn\u00edm souboru bmcfwu.cfg, kter\u00fd ur\u010duje cestu k obrazu aktualizovan\u00e9ho firmwaru. P\u0159i dal\u0161\u00edm aktualizaci, kterou lze iniciovat p\u0159\u00edkazem v IPMI, bude tento parametr zpracov\u00e1n BMC a pou\u017eit jako sou\u010d\u00e1st vol\u00e1n\u00ed popen() ve form\u00e1tu \u0159et\u011bzce pro \/bin\/sh. Vzhledem k tomu, \u017ee \u0159et\u011bzec pro sestaven\u00ed shellov\u00e9ho p\u0159\u00edkazu se vytv\u00e1\u0159\u00ed pomoc\u00ed vol\u00e1n\u00ed snprintf() bez \u0159\u00e1dn\u00e9ho \u010di\u0161t\u011bn\u00ed speci\u00e1ln\u00edch znak\u016f, \u00fato\u010dn\u00edci mohou podstr\u010dit sv\u016fj k\u00f3d k proveden\u00ed. Pro zneu\u017eit\u00ed zranitelnosti je pot\u0159eba m\u00edt pr\u00e1va, kter\u00e1 umo\u017e\u0148uj\u00ed odeslat p\u0159\u00edkaz na BMC kontrol\u00e9r prost\u0159ednictv\u00edm IPMI (p\u0159i administr\u00e1torsk\u00fdch pr\u00e1vech na serveru lze odeslat p\u0159\u00edkaz IPMI bez dal\u0161\u00ed autentizace).<\/p>\n

Spole\u010dnosti Gigabyte a Lenovo byly o probl\u00e9mech informov\u00e1ny ji\u017e v \u010dervenci 2018 a stihly vydat aktualizace p\u0159ed ve\u0159ejn\u00fdm odhalen\u00edm informac\u00ed. Spole\u010dnost Lenovo vyu\u017eila<\/a><\/noindex> vydala aktualizace firmwaru 15. listopadu 2018 pro servery ThinkServer RD340, TD340, RD440, RD540 a RD640, ale odstranila v nich pouze zranitelnost, kter\u00e1 umo\u017e\u0148ovala prov\u00e1d\u011bt injektov\u00e1n\u00ed p\u0159\u00edkaz\u016f, proto\u017ee b\u011bhem v\u00fdvoje \u0159ady server\u016f na b\u00e1zi MergePoint EMS v roce 2014 ov\u011b\u0159ov\u00e1n\u00ed firmware pomoc\u00ed digit\u00e1ln\u00edho podpisu je\u0161t\u011b nebylo b\u011b\u017en\u011b roz\u0161\u00ed\u0159en\u00e9 a p\u016fvodn\u011b nebylo uvedeno.<\/p>\n

8. kv\u011btna tohoto roku spole\u010dnost Gigabyte vydala aktualizace firmwaru pro z\u00e1kladn\u00ed desky s ovlada\u010dem ASPEED AST2500, ale stejn\u011b jako Lenovo odstranila pouze zranitelnost souvisej\u00edc\u00ed s injektov\u00e1n\u00edm p\u0159\u00edkaz\u016f. Zraniteln\u00e9 desky na b\u00e1zi ASPEED AST2400 zat\u00edm z\u016fst\u00e1vaj\u00ed bez aktualizace. Spole\u010dnost Gigabyte tak\u00e9 prohl\u00e1sil<\/a><\/noindex> p\u0159ejde na pou\u017e\u00edv\u00e1n\u00ed firmwaru MegaRAC SP-X od spole\u010dnosti AMI. Nov\u00e9 firmwary zalo\u017een\u00e9 na MegaRAC SP-X budou tak\u00e9 nab\u00edzeny pro syst\u00e9my, kter\u00e9 byly d\u0159\u00edve dod\u00e1v\u00e1ny s firmwarem MergePoint EMS. Toto rozhodnut\u00ed bylo u\u010din\u011bno po prohl\u00e1\u0161en\u00ed spole\u010dnosti Vertiv o ukon\u010den\u00ed podpory platformy MergePoint EMS. O aktualizaci firmwaru na serverech vyr\u00e1b\u011bn\u00fdch spole\u010dnostmi Acer, AMAX, Bigtera, Ciara, Penguin Computing a sysGen na z\u00e1klad\u011b desek Gigabyte a vybaven\u00fdch zraniteln\u00fdmi firmwary MergePoint EMS se zat\u00edm nic neozn\u00e1milo.<\/p>\n

P\u0159ipom\u00edn\u00e1me, \u017ee BMC je specializovan\u00fd kontroler, kter\u00fd je instalov\u00e1n v serverech, m\u00e1 vlastn\u00ed CPU, pam\u011b\u0165, \u00falo\u017ei\u0161t\u011b a senzory, a poskytuje n\u00edzko\u00farov\u0148ov\u00e9 rozhran\u00ed pro monitorov\u00e1n\u00ed a \u0159\u00edzen\u00ed serverov\u00e9ho vybaven\u00ed. Pomoc\u00ed BMC je mo\u017en\u00e9 nez\u00e1visle na opera\u010dn\u00edm syst\u00e9mu b\u011b\u017e\u00edc\u00edm na serveru sledovat stav senzor\u016f, spravovat nap\u00e1jen\u00ed, firmwary a disky, organizovat vzd\u00e1len\u00e9 bootov\u00e1n\u00ed p\u0159es s\u00ed\u0165, poskytovat konzoli pro vzd\u00e1len\u00fd p\u0159\u00edstup atd.<\/p>\n

<\/a><\/noindex><\/p>\n

Zdroj: opennet.ru<\/a><\/p>","protected":false,"gt_translate_keys":[{"key":"rendered","format":"html"}]},"excerpt":{"rendered":"

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